SHORTWHEAT

Rht (semi-dwarf) alleles were introduced from exotic donors into European wheat breeding populations and used extensively by breeders over the last 20 years. While these genes considerably increased the yield potential of modern wheat varieties, they may have also rendered them more susceptible to Fusarium head blight (FHB) causing problems with mycotoxin contamination of food and feed. However, the (mutant) Rht genes vary in their physiological mechanism – gibberellic acid (GA) insensitivity – and, hypothetically, their effect on FHB susceptibility since the pathogenesis-related signal transduction pathway may be affected by GA. In this project a consortium of three practical wheat breeders and a public centre of excellence in the field of molecular plant breeding, assisted by a private biotechnological service lab, plan to analyse the association of various Rht alleles with FHB susceptibility and use a combination of marker-assisted selection (MAS) and doubled-haploid (DH) technology for accelerated crop improvement. In project phase 1, published microsatellite markers of Rht genes will be used to diagnose a set of current European varieties with known agronomic and FHB phenotype. In field trials, the association of specific Rht alleles with FHB susceptibility will be investigated among the lines, but also in an existing FHB resistance gene mapping population and backcross-derived near-isogenic lines carrying major FHB QTL from Sumai3 or Frontana. In phase 2, Rht alleles from useful semi-dwarf donor lines will be integrated into high-yielding, but tall, germplasm with excellent quantitative FHB resistance. In phase 3 (post 3-year ETB funding period), practical development of new varieties will continue by extensive multilocation field trials and limited genotyping work. The approach is novel: here the agronomic performance of resistant lines will be improved by MAS focusing on well described major genes whereas the conventional approach is to improve the resistance by MAS for multiple QTL (quantitative trait locus) alleles derived from exotic sources. FHB is considered the most serious cereal disease in Europe, even more so after in 2005 the EU has regulated maximum trichothecene mycotoxin levels in food and feed grain. FHB-resistant, semi-dwarf varieties would help increase yields, lower production costs (fungicide use) and improve food and feed security. The distribution of work among the partner institutions is outlined in the table. The cooperation of breeders in Germany, Austria and France should facilitate the improvement of wheats for major European markets representing a broad range of environments. The cereal seed company SMEs involved would gain expertise and efficiency by implementing molecular breeding techniques. Networking with public plant molecular genetics institutions would help close the widening gap between the fast-growing cereal genomics knowledge base and the world of practical wheat breeding